Question: The garden club earned $\$15$ per hour by weeding neighborhood gardens for $t$ hours. A generous donor has agreed to double their earnings. How much did the garden club earn in all? Write your answer as an expression. $\$$
Answer: Let's see what happens as the number of hours increases: Number of hours Total earnings ${1}$ $15 \cdot {1} \cdot 2 = 30$ ${2}$ $15 \cdot {2} \cdot 2 = 60$ ${3}$ $15 \cdot {3} \cdot 2 = 90$ Number of hours Total earnings ${t}$ $15 \cdot {t} \cdot 2 = 30t$ The garden club earned $\$30t$ in all.